Regarding Christina, she isn't good enough now, but that doesn't mean she won't be in 3 years. She has the most technical content out of all the US ladies right now and one of the only ones with a consistent 3-3, and her jumps are not only consistent but get +GOE. Her spins and spirals need work, yes, but these days they don't count for much anyway, and those things are easier to learn than a 3f-3t, plus she is already getting the levels as is. Her PCS aren't great but those should improve if she can perform well consistently on the senior ranks, which shouldn't be an issue considering her jumps are very solid and she doesn't seem to have any major issues regarding pressure. She's also going to have basically all of Orser's attention, at least for the upcoming season, which should help. This season didn't go as well as a lot of people hoped, but I think that was mainly due to 1.) her growthspurt and 2.) peaking too early in the season. The growing pains should be done, and she will likely figure out a plan with Brian to prevent peaking so early (ie at her 1st GP like she did this season) next season.
This is just my opinion but I think Christina has better odds of becoming a medal contender internationally than Agnes does. Agnes is on a faster track for right now, which is why she's beating Christina, but I sort of feel like she's as good now as she's ever going to be, and could potentially regress. With Christina I don't feel the same way. Agnes has the quintessential Tom Z flaws - slow, a little generic, etc and if she stays with Tom I feel like those weaknesses won't be addressed. Christina, OTOH, has Orser and Wilson on her team, and has already improved tremendously under that team. The other thing about Agnes is her height. She towers over the competition, and for now she can still pull the jumps off because she's thin as a rail, but that might change in coming years and she could end up like Kostner or Phanuef, very talented, but very inconsistent. I know Christina got a lot taller this season too, but she's still a lot smaller than Agnes so I don't worry about her as much. If Agnes leaves Tom Z, then I think she still has a good shot at making the Olympic Team in Sochi and becoming a medal contender, but if she doesn't, I don't know.